Downhole straddle system

1. A downhole straddle system for sealing off a damaged zone in a well tubular metal structure in a well having a top, comprising:

a straddle assembly having a first end, a second end closest to the top, an inner face, a first hydraulic expandable annular barrier and a second hydraulic expandable annular barrier,

a downhole tool assembly having a hydraulic operated deployment tool for releasable connecting the downhole tool assembly to the second end of the straddle assembly, the downhole tool assembly further comprising a first sealing unit arranged above the first hydraulic expandable annular barrier and the second hydraulic expandable annular barrier and configured to seal against the inner face of the straddle assembly, and

a closing unit configured to close the first end of the straddle assembly,

wherein the downhole tool assembly further comprising a sealing device arranged above the deployment tool and the first sealing unit, the sealing device has an annular sealing element having a first outer diameter in a first condition and a second outer diameter being larger than the first outer diameter in a second condition for sealing against an inner face of the well tubular metal structure, the sealing device comprises a fluid channel to fluidly connect an inside of the straddle assembly with the well tubular metal structure above the sealing device when the sealing device is in the second condition for expanding the first hydraulic expandable annular barrier and the second hydraulic expandable annular barrier.

2. A downhole straddle system according to claim 1 , wherein the sealing device is electrically operated through a wireline, such as an electric line.

3. A downhole straddle system according to claim 1 , wherein the closing unit is a plug, a shear ball seat or a rupture disc arranged in the first end of the straddle assembly.

4. A downhole straddle system according to claim 1 , wherein the downhole tool assembly comprises the closing unit, the downhole tool assembly comprises a tubular section extending below the first sealing unit, the closing unit comprises a closed end of the tubular section and a second sealing unit arranged below the first hydraulic expandable annular barrier and the second hydraulic expandable annular barrier.

5. A downhole straddle system according to claim 4 , wherein the tubular section has at least one opening between the first hydraulic expandable annular barrier and the second hydraulic expandable annular barrier.

6. A downhole straddle system according to claim 1 , wherein the sealing device comprises an electric motor for operating the sealing element between the first outer diameter and the second outer diameter.

7. A downhole straddle system according to claim 1 , wherein the deployment tool comprises engagement elements for engaging the inner face of the straddle assembly at the second end.

8. A downhole straddle system according to claim 1 , wherein the first hydraulic expandable annular barrier and the second hydraulic expandable annular barrier each comprises an expandable metal sleeve.

9. A downhole straddle system according to claim 7 , wherein the deployment tool comprises a fail-safe arrangement configured to maintain the engagement elements in engagement with the straddle assembly in a first position and at a predetermined pressure move to a second position in which the engagement elements are allowed to retract from engagement with the straddle assembly.

10. A downhole straddle system according to claim 9 , wherein the fail-safe arrangement comprises a breakable element.

11. A downhole straddle system according to claim 9 or 10 , wherein the fail-safe arrangement comprises a tubular piston movable from the first position to the second position of the deployment tool when influenced by a pressure above a certain pressure.

12. A downhole well system comprising:

a well tubular metal structure having a top and a damaged zone,

a downhole straddle system according to claim 1 configured to be arranged opposite the damaged zone for arranging a straddle assembly over the damaged zone, and

a pump arranged at the top of the well tubular metal structure configured to pressurise the well tubular metal structure.

13. A repairing method, comprising:

detecting a damaged zone of a well tubular metal structure,

arranging a downhole straddle system according to claim 1 opposite the damaged zone,

activating the annular sealing element of the sealing device,

pressurising the well tubular metal structure above the sealing device,

expanding the first hydraulic expandable annular barrier and the second hydraulic expandable annular barrier via the fluid channel of the sealing device for isolating the damaged zone,

deactivating the annular sealing element of the sealing device,

releasing the deployment tool from the straddle assembly, and

removing the downhole tool assembly from the well tubular metal structure.

14. A repairing method according to claim 13 , whereby the sealing device is electrically operated through a wireline, such as an electric line.

15. A repairing method according to claim 13 , whereby the well tubular metal structure is pressurised above a certain pressure whereby the deployment tool is released from the straddle assembly.